testing of coax cable for a system upgrade?

[Gavin John Hyde]

Just been speaking to a possible customer, she wants CCTV upgrading in her business. Currently has an old system with co-axial cables and seperate leads for power at each camera.
She wants as little interruption as possible with the new digital cameras, I am thinking power over coax... I have done plenty of power over Ethernet and basically works in similar way. Some of the new HikVision stuff looks quite good.
How would I go about confirming the coax is up to the job of carrying both the signal and power? Some old coax was poorly made and for all i know could be falling apart in the walls/ceiling etc...
What tests do I do to establish it is good for using on the new cameras? continuity? IR @ 250v? even though it doesn't carry mains and is usually at or around 20v DC
This has advantages as it means no routing of replacement cables and I can literally connect new cameras and terminate accordingly at the new DVR. saves a lot of time and money.
Thoughts and experience of power over coax systems please?

 

[Squid]

I don't know much about POC as the setup I have at home is POE and I can recommend the Hikvision hardware, have a read here,

Hikvision Europe - http://www.hikvision.com/europe/Press-Release-details_71_i18468.html

I bought my stuff from here, they have a 6% off deal every so often.

CCTV Kits | CCTV Systems | Trade CCTV | CCTV Seller - http://cctvseller.co.uk

 

[Squid]

Just re read you post, wasn't Coax 50 OHM so testing would be required, how old is the install as it shouldn't deteriorate as its copper unless the mice and rats have been at it, if you need to guarantee your work then just install POE and the cabling for peace of mind and less come backs, charity tends to bite you in the arse.

 

[Gavin John Hyde]

Just re read you post, wasn't Coax 50 OHM so testing would be required, how old is the install as it shouldn't deteriorate as its copper unless the mice and rats have been at it, if you need to guarantee your work then just install POE and the cabling for peace of mind and less come backs, charity tends to bite you in the arse.

The current stuff is a mix of late 90's with some extra cams added in early 2000's.
My first thought was PoE but by using the existing cables it means less mess, time and inconvenience to the customer, I would include in the terms that Im not responsible for cables etc and warranty extends only to what I supply, She seemed okay with that on the phone. i shall have a look on Saturday when I price it up properly.

I do like the HikVision and there access control stuff is great, they make brilliant intercom systems for apartments.. so easy to install compared to more well established names

 

[littlespark]

If the CCTV is really old, the coax might only be good for analogue signals. Try and send digital (which I would think this new system would be) and there will be signal loss and interference.

You've got power for the cameras. what about wireless signal transmission?

 

[Gavin John Hyde]

If the CCTV is really old, the coax might only be good for analogue signals. Try and send digital (which I would think this new system would be) and there will be signal loss and interference.

You've got power for the cameras. what about wireless signal transmission?

Wireless is the fall back if the cables arent upto the job, she seems keen on wired. i think more because it makes sense and she understands how it works! I shall do my best sales pitch on saturday! I wont over sell the job and install a casino grade system ££££ but will explain pros and cons of each type to her

 

[Squid]

The current stuff is a mix of late 90's with some extra cams added in early 2000's.
My first thought was PoE but by using the existing cables it means less mess, time and inconvenience to the customer, I would include in the terms that Im not responsible for cables etc and warranty extends only to what I supply, She seemed okay with that on the phone. i shall have a look on Saturday when I price it up properly.

I do like the HikVision and there access control stuff is great, they make brilliant intercom systems for apartments.. so easy to install compared to more well established names

Being okay over the phone is one thing, you know how customers can be once you start the work, cover your back. I have a Hikvision NVR and a couple of cameras that I have been playing around with.

Coax will last, its been used for TV aerials for years the only thing to consider is the quality of the signal sent from the camera to the recording unit.

 

[mhar]

Apart from the impedence, the frequency is the most important consideration.
Older cctv worked on the vhf band and, as attenuation is directly related to frequency, these vhf signals would travel fine down any old co-ax. If you are proposing higher frequency signals you will need to ensure that the cable is suitable for those frequencies.
The cable should be marked on the sheath and you will have to look up the data sheets to assess suitability.
Usually shotgun cable was used (not what the sky dickheads incorrectly refer to as shotgun cable which is just a twin cable) so the power is carried alongside the cable